Demographic data on 5,060 individually marked plants of the endemic State and federally listed Polygala lewtonii (Lewton's milkwort; Polygalaceae) were collected from December 2001 to December 2017 at the Lake Wales Ridge National Wildlife Refuge Carter Creek in south central Florida, USA. Data collection is still ongoing. In 220 permanent 25 cm radius circular plots, plants were marked with plastic toothpicks and wire stake flags with a unique identification number. Data collection occurred quarterly with survival and recruitment recorded in March, June, September and December and more detailed measures of size and fecundity taken in March. This species is amphicarphic with both showy-open flowers produced in spring (chasmogamy) and closed, self-pollinating flowers both above- and belowground produced in late summer (cleistogamy). Therefore, our fecundity data are based only on chasmogamy. This dataset also captures post-fire mortality and recruitment events following four prescribed burns.